ALBERT

Description: Enhanced angiogenesis is a hallmark of cancer. Pleiotrophin (PTN) is an angiogenic factor that is produced by many different human cancers and stimulates tumor blood vessel formation when it is expressed in malignant cancer cells. Recent studies show that monocytes may give rise to vascular endothelium. In these studies, we show that PTN combined with macrophage colony-stimulating factor (M-CSF) induces expression of vascular endothelial cell (VEC) genes and proteins in human monocyte cell lines and monocytes from human peripheral blood (PB). Monocytes induce VEC gene expression and develop tube-like structures when they are exposed to serum or cultured with bone marrow (BM) from patients with multiple myeloma (MM) that express PTN, effects specifically blocked with antiPTN antibodies. When coinjected with human MM cells into severe combined immunodeficient (SCID) mice, green fluorescent protein (GFP)–marked human monocytes were found incorporated into tumor blood vessels and expressed human VEC protein markers and genes that were blocked by anti-PTN antibody. Our results suggest that vasculogenesis in human MM may develop from tumoral production of PTN, which orchestrates the transdifferentiation of monocytes into VECs.

Description: Abstract 4713 Background AML with t(8;21) is known to have a more favorable outcome when treated with adequate chemotherapy and supportive care. There have been minimal data on the characteristics and outcome of AML with this translocation in low-income countries. Aim We analyze the clinical and biological characteristics of a large population of children and adults with AML in Casablanca who had t(8;21) in relation to response, event-free (EFS) and overall survival (OS). Methods From 4/1/03 to 3/31/09, eligible patients were treated on the AML-MA2003 protocol at a single center. For patients presenting with WBC〉50,000, hydroxyurea (HU) was given for 4 days prior to initiation of standard induction. Treatment included two induction courses of cytarabine, 200 mg/m2/d (days 1-7) and daunomycin 50 mg/m2/d (days 1-3); consolidation was stratified by age: those '20 years had two courses of Capizzi high-dose cytarabine, 2 g/m2 q 12h (days 1-4) with L-asparaginase, 6000 units/m2 day 4; those 〉20 years had one or two courses of high-dose cytarabine, 1 g/m2 q 12h (days 1-4) with daunomycin 50 mg/m2/d (day 1-3), and maintenance with oral 6-mercaptopurine 60 mg/m2/d and weekly sc cytarabine 40 mg/m2 for 18 months. Events included death, relapse, progression, and abandonment. Results 85 of 535 (15.8%) patients with karyotype results had t(8;21), including 40 with only t(8;21), 25 with additional loss of a sex chromosome, 5 with del (9), and 15 with other cytogenetic abnormalities. Characteristics of the t(8;21) group are shown in the Table. Five adults were ineligible for protocol therapy, due to secondary AML (n=1), refused (n=1) and early death (n=3). Of 33 children (age 〈 20 years), 28 completed all 4 courses of planned therapy. Five deaths occurred on therapy (1 failure, 4 toxicity) and 11/28 relapsed later, 8-14 months after end therapy. Of 47 adults who received the first induction course, 35 went on to 2nd induction, 34 received 1st consolidation, 22 completed both courses of induction and consolidation, and 20 completed maintenance. There were 12 deaths on therapy and 12 relapses after therapy completion. Overall, 30/80 patients did not complete prescribed therapy: 14 deaths, 1 failure, 4 abandonment, 11 complete remission). 7/8 children and 4/4 adults with t(8;21) had an early response (50% decrease in blasts) to HU. The complete remission rate (CR) after two courses of induction therapy was 91% for children and 72.5% for adults. The 2-year EFS and OS for the patients with t(8;21) was 32% (standard error [SE] 6.3%) and 59% (SE 7.3%) respectively. There was not a significant difference in 2-year EFS by sex (p=0.18), age ' 20 years vs older (p= 0.08), or presence of additional cytogenetic abnormalities accompanying the t(8;21) (p=0.98) Conclusions t(8;21) in Morocco occurred in 15.8% of cases, more frequently than the 7 to12% reported. It was associated with a high incidence of extramedullary disease, FAB M2, frequent deletion of a sex chromosome, preponderance of males, and young age. A third of these favorable-risk AML patients survive event-free 2 years from diagnosis despite the problem of abandonment of therapy and suboptimal supportive care. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2968 Poster Board II-944 Previously, we identified and validated PIM1 as a differentially expressed gene in mantle cell lymphoma (MCL) patient samples. Further, we have shown PIM1 to be a significant prognostic biomarker in MCL. PIM1 is a serine/threonine kinase that is transcriptionally regulated by cytokines, mitogens, and numerous growth factors. PIM1 cooperates with other oncogenes in tumorigenesis and has been implicated in the development of leukemias, lymphomas, late progression events, and most recently in prostate cancer. PIM1 is overexpressed in aggressive lymphomas, such as the blastoid variant of MCL, and the ABC-subtype of diffuse large B-cell lymphomas (DLBCL). Here, we tested the in vivo cooperation of PIM1 with TCL1 in murine lymphomagenesis by producing double transgenic murine strains. PIM1 transgenic mice overexpress murine PIM1 under the control of the immunoglobulin enhancer Eμ. TCL1 transgenic mice (pEμ-B29-TCL1) fail to down-regulate TCL1 expression in mature B and T cells and provide a unique model for mature B-cell malignancies. We hypothesized that PIM1 would either accelerate TCL1-driven lymphomagenesis, result in the development of immature lymphomas, or both. Lymphoid malignancies were examined by immunohistochemistry and classified by a hematopathologist according to “Mouse Models of Human Blood Cancers” (Li et al., 2008). A Kaplan-Meier plot demonstrated statistically significant acceleration of lymphomagenesis in the PIM1/TCL1 transgenic mice when compared with the single transgenic strains. The median lymphoma-free survival for TCL1 single transgenic mice, PIM1 single transgenic mice, or PIM1/TCL double transgenic mice were 10.0 months, 16.0 months, and 8.5 months, respectively. The results were statistically significant: TCL1 vs. PIM1/TCL1 (p=0.0008), PIM1 vs. PIM1/TCL1 (p12 months of age) B-cell lymphomas. The most common lymphomas in PIM1 single transgenic were low-grade B-cell lymphomas [12 of 31 (38.7%)], mainly follicular lymphomas. A minority of PIM1 single transgenic mice developed aggressive lymphomas [6 of 31 (19.4%)], including DLBCL and Burkitt's lymphoma. In contrast, the majority of TCL1 transgenic mice developed aggressive B-cell lymphomas [21 of 36 (58.3%)], mainly DLBCL, lymphohistiocytic subtype. The majority of PIM1/TCL1 double transgenic mice also developed aggressive B-cell lymphomas [20 of 34 (58.8%)], mainly DLBCL, lymphohistiocytic subtype. The low-grade lymphomas that developed in PIM1/TCL1 mice included 5 cases of lymphoplasmacytic lymphoma (LPL); one of these cases had transformed in addition to a DLBCL. Further, endogenous expression of PIM kinase family members was investigated in a human lymphoma cell line bank (n=40) by quantitative real-time PCR. PIM1, PIM2, and PIM3 were found to be overexpressed in cell lines derived from human lymphoid malignancies of multiple histologies. In summary, aberrant PIM1 overexpression in TCL1 transgenic mice accelerated the development of mature, aggressive B-cell lymphomas. The classification of lymphomas in PIM1/TCL1 mice revealed similar histologies as in TCL1 single transgenic mice, mainly DLBCL. Single transgenic PIM1 mice developed low-grade B-cell lymphomas after prolonged observation time. The expression of all 3 PIM kinase family members in human lymphomas implies that pan-PIM kinase inhibitors should be developed as a potential mechanism of drug resistance to more restricted PIM inhibitors could be compensatory overexpression of the non-targeted Pim family members. A clinical trial with a pan-PIM inhibitor is currently ongoing. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3454 Poster Board III-342 Non-Hodgkin's lymphoma (NHL) is a heterogeneous clinicopathologic entity characterized by distinct cells of origin and unique cytogenetic and molecular aberrations. Recently, we found by transcription profiling of CCAAT/enhancer-binding proteins (CEBPs) that they could regulate expression of the core circadian clock gene Period (PER) 2. We now report that C/EBPalpha and PER2 are highly dysregulated specifically in diffuse large B-cell lymphoma (DLBCL), one of the commonest type of high-grade NHL. Real time RT-PCR analysis of human samples of diffuse large B-cell lymphoma (DLBCL; n = 37), mantle cell lymphoma (MCL; n = 12), follicular lymphoma (FL; n = 12), and Burkitt's lymphoma (BL; n = 6) compared to normal tonsil samples (n = 10) revealed a markedly downregulated expression of both CEPBalpha and PER2 specifically in the DLBCL samples. The expression of these two genes was also significantly decreased in the 7 human DLBCL cell lines, OCI-Ly1, -Ly4, -Ly7, -LY10, and SUDHL-4, -6, -16. In contrast, mRNA levels of CEBPalpha and PER2 in samples of MCL, FL or BL showed no significant change compared to the normal tonsils, which were confirmed in cell lines of MCL (SP-49, Jeko-1, NCEB-1), FL (FLK-1) and BL (Daudi). Moreover, PER1, another important circadian rhythm gene of the Period family, showed no differences of expression in any of the NHL samples compared to control lymph nodes. The murine pro-B lymphoid cell line Ba/F3 had low levels C/EBPalpha, and forced expression of the transcription factor resulted in decreased growth and increased apoptosis as measured by trypan blue cell count and Annexin V (FACS), suggesting that this transcription factor may induce apoptosis in lymphoma. Moreover, transfection of Ba/F3 cells with a zinc-inducible CEBPalpha gene increased PER2 expression levels by 7-fold. The analysis of the PER2 promoter region showed several potential CEBPalpha binding sites, and chromatin immunoprecipitation (ChIP) as well as luciferase reporter assay experiments using Ba/F3 cells revealed that CEBPalpha can directly bind to the PER2 promoter and induce its expression. Interestingly, treatment of Ba/F3 and several DLBCL cell lines (Ly-4, SUDHL-4, -6) with the histone deacetylase-inhibitor, SAHA, significantly induced expression of both CEBPalpha and PER2, which was associated with inhibition of cell growth and apoptosis. Our further studies explored the consequences of expressing PER2 on cell proliferation. Forced expression of PER2 in Ba/F3 cells led to substantial growth reduction, G0/G1 cell cycle arrest, and altered protein expression of apoptosis-related genes. The protein level of Bcl-X(L) was downregulated, whereas levels of Bax and PARP cleavage activity were upregulated compared with control cells transfected with empty plasmid. In summary, our results show for the first time that both CEBPalpha and its key downstream target circadian clock gene, PER2, are highly dysregulated in DLBCL. Our data strongly suggest that these genes may play a role in the pathogenesis of this disorder and should be considered for therapeutic manipulation. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 4964 POEMS syndrome is characterized by chronic progressive polyneuropathy (P), organomegaly (O), endocrinopathy (E), serum monoclonal protein (M), and skin changes (S). The bone lesions are typically sclerotic and may be minor in number or aymptomatic. Autologous peripheral blood stem cell transplant (APBSCT) has been reported to reverse major clinical manifestations of this disease. The peripheral neuropathy is often motor and sensory, painful in many cases, and asymmetric in distribution, and is often the major disease manifestation that affects patient performance status, and requires treatment. We report a patient case of POEMS where polyneuropathy was debilitating, confirmed by nerve conduction studies (NCS) with rapid clinical improvement on lenolidomide treatment and objective reversal of findings on NCS. The patient is a 54 year old man who developed slight leg weakness while exercising, and progressive severe lower back pain radiating down his right leg more than left. Plain X-ray showed an abnormality of the T4 and L3 vertebrae, and MRI showed a hypodense abnormality of the T3 vertebra and sclerotic area at the L2-3 vertebra. CT guided biopsy of these lesions showed plasma cells staining positive for CD 138 ; karyotype on the biopsy lesion was negative. The skeletal X-ray series was negative other than T4 and L3. Bone marrow biopsy showed no increase in plasma cells. Body CT showed multiple sclerotic lesions at the bodies of the pubis bones, left ischial tuberosity, femoral heads (left more than right), right sacrum, L3 and T12 vertebral body. PET scan showed uptake in these areas, SUV 3-4.6 The next MRI suggested 2 new sacral lesions and a new T7 lesion. At presentation, he had very remarkable motor and sensory changes in the right leg greater than the left with sensory neuropathy, proprioception and parasthesias. He had dysesthesias, parasthesias and loss of sensation. Nerve conduction studies showed complete loss of motor potentials in the right peroneal and right posterior tibial area and sensory abnormalities in the right sural nerve. He had bilateral foot drop with poor of balance and used a rolling walker, and subjective sensory loss and numbness of the distal extremities with dysthesias and parasthesias. Motor exam of lower extremities notable for 5/5 in the proximal muscles, foot and toe flexion 4/5 bilaterally. Upper extremities and cranial nerves intact except for poor hand grip strength. Laboratory Data SPEP showed small monoclonal IgG lambda band of 0.3 g/dl, immunofixation (urine) showed monoclonal free lambda light chains. Serum free light chains showed a ratio reversal of Lambda 44 to kappa 28. Quantitative immunoglobulins UPEP, CBC and ESR were within normal range. Patient's bone marrow was negative for multiple myeloma and amyloidosis. Lenalidomide was started at 15 mg/day for 21 days of a 28 day cycle with once weekly dexamethasone 40mg. By the second month patient was on therapy, his performance status improved to ECOG 1, with resolution of pain within the first cycle. Repeat nerve conduction studies after 4 cycles of Len/Dex confirmed marked improvement of motor and sensory nerve potentials. Patient underwent APBSCT and had a continued clinical improvement for two years, and was able to return to full time work. Conclusion Lenalidomide is an effective treatment for POEMS syndrome, with rapid and objectively documented improvement in polyneuropathy. As POEMS may be a cytokine-mediated disorder, the immunomodulatory effects of lenolidomide may explain its benefit in these patients. Disclosures Mohrbacher: Celgene: Speakers Bureau. Off Label Use: lenolidomide.